1. Field of the Invention
This invention relates to a contact of a connector, and more particularly to a contact suitable for use in small-sized connectors for information transmission appliances.
2. Description of the Prior Art
With requirement of signal transmission at higher speed in information transmission line, it has been required to shorten lengths of conductive portions of contacts in connectors incorporated in information transmission lines. On the other hand, the connectors to be used in information transmission appliances have been intensively required to be small-sized, inasumuch as these appliances have been required to be small-sized. In this case, an indispensable condition to fulfill the requirement of the small-sized connectors is to achieve small-sized contacts.
Under the circumstances, however, such small-sized contacts should still realize reliable and stable contacting conditions with contacts of mating connectors inserted and connected or contacts of printed circuit boards in order to perform their inherent function. On the contrary, if the contacts are small-sized to shorten the signal transmission line, contacting resilient pressure of the contacts usually becomes insufficient to adversely affect the contacting conditions. Accordingly, the small-sizing of the contacts would encounter an unavoidable limitation.
Various attempts have therefore been effected in order to obtain sufficient contacting resilient pressures in sufficiently small-sized contacts. As shown in FIG. 1, for example, a contact 1 is bent at its mid portion or midway 1a into a wide S-shape, and its distal end 1b is then folded back to its holded portion 1c so as to abut against a surface of a connector housing 2. In this manner, the S-shaped midway 1a and the distal end 1b provide a contacting resilient pressure required when a contact 3 of a mating connector is inserted into this connector to be into contact with the contact 1. With this arrangement, however, a signal flowing into the contact 1 at its contacting point 1d passes through the S-shaped bent portion 1a to a connneting portion 1e as shown by arrows in the drawing, so that the signal transmission passage is much longer than that in a conventional contact 1, for example, as shown in FIG. 2.
In an alternative example as shown in FIG. 3, a contact 1 is bent so as to form a loop to bring its distal end 1b into the proximity of a holded portion. In order to obtain a resilient pressure with this arrangement substantially equivalent to the pressure of the contact shown in FIG. 1, however, the bent portion 1f of the loop should be fairly large, so that an overall length of the contact becomes much longer. As the result, the contact does not fulfill the requirement of the small-size and fails to shorten the signal transmission passage because a signal flowing at a contacting portion 1d into the contact passes through the loop 1f into a connecting portion 1e as shown by arrows in the drawing.
In a further alternative example, as shown in FIG. 4, a contact 1 comprises an upper portion 1g extending much longer than that of the contact shown in FIG. 2 and abutting with its distal end 1b against a surface of a housing 2 in order to obtain a predetermined resilient pressure. With this arrangement, a signal flowing at a contacting portion 1d passes straight into the contact as shown by an arrow in the drawing, so that the length of the signal transmission passage is sufficiently shortened in comparison with those in FIGS. 1 and 3. On the other hand, however, the upper portion 1g should be considerably elongated in order to obtain a resilient pressure substantially equivalent to that of the contact shown in FIG. 1, so that such an elongated contact does not fulfill the requirement of the small-sized contact. In addition, a distance from an entrance of this connector for a mating connector to the contacting portion 1d becomes considerably long, so that a contact of the mating connector is also unavoidably long so as to elongate the signal transmission passage of the mating connector to give rise to reduction in signal transmission speed.